contrib/bind9/lib/dns/rdataslab.c

   1 /*
   2  * Copyright (C) 2004-2009  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2003  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: rdataslab.c,v 1.48.50.2 2009/01/18 23:47:40 tbox Exp $ */
  19
  20 /*! \file */
  21
  22 #include <config.h>
  23
  24 #include <stdlib.h>
  25
  26 #include <isc/mem.h>
  27 #include <isc/region.h>
  28 #include <isc/string.h>         /* Required for HP/UX (and others?) */
  29 #include <isc/util.h>
  30
  31 #include <dns/result.h>
  32 #include <dns/rdata.h>
  33 #include <dns/rdataset.h>
  34 #include <dns/rdataslab.h>
  35
  36 /*
  37  * The rdataslab structure allows iteration to occur in both load order
  38  * and DNSSEC order.  The structure is as follows:
  39  *
  40  *      header          (reservelen bytes)
  41  *      record count    (2 bytes)
  42  *      offset table    (4 x record count bytes in load order)
  43  *      data records
  44  *              data length     (2 bytes)
  45  *              order           (2 bytes)
  46  *              meta data       (1 byte for RRSIG's)
  47  *              data            (data length bytes)
  48  *
  49  * If DNS_RDATASET_FIXED is defined to be zero (0) the format of a
  50  * rdataslab is as follows:
  51  *
  52  *      header          (reservelen bytes)
  53  *      record count    (2 bytes)
  54  *      data records
  55  *              data length     (2 bytes)
  56  *              data            (data length bytes)
  57  *
  58  * Offsets are from the end of the header.
  59  *
  60  * Load order traversal is performed by walking the offset table to find
  61  * the start of the record (DNS_RDATASET_FIXED = 1).
  62  *
  63  * DNSSEC order traversal is performed by walking the data records.
  64  *
  65  * The order is stored with record to allow for efficient reconstruction
  66  * of the offset table following a merge or subtraction.
  67  *
  68  * The iterator methods here currently only support DNSSEC order iteration.
  69  *
  70  * The iterator methods in rbtdb support both load order and DNSSEC order
  71  * iteration.
  72  *
  73  * WARNING:
  74  *      rbtdb.c directly interacts with the slab's raw structures.  If the
  75  *      structure changes then rbtdb.c also needs to be updated to reflect
  76  *      the changes.  See the areas tagged with "RDATASLAB".
  77  */
  78
  79 struct xrdata {
  80         dns_rdata_t     rdata;
  81         unsigned int    order;
  82 };
  83
  84 /*% Note: the "const void *" are just to make qsort happy.  */
  85 static int
  86 compare_rdata(const void *p1, const void *p2) {
  87         const struct xrdata *x1 = p1;
  88         const struct xrdata *x2 = p2;
  89         return (dns_rdata_compare(&x1->rdata, &x2->rdata));
  90 }
  91
  92 #if DNS_RDATASET_FIXED
  93 static void
  94 fillin_offsets(unsigned char *offsetbase, unsigned int *offsettable,
  95                unsigned length)
  96 {
  97         unsigned int i, j;
  98         unsigned char *raw;
  99
 100         for (i = 0, j = 0; i < length; i++) {
 101
 102                 if (offsettable[i] == 0)
 103                         continue;
 104
 105                 /*
 106                  * Fill in offset table.
 107                  */
 108                 raw = &offsetbase[j*4 + 2];
 109                 *raw++ = (offsettable[i] & 0xff000000) >> 24;
 110                 *raw++ = (offsettable[i] & 0xff0000) >> 16;
 111                 *raw++ = (offsettable[i] & 0xff00) >> 8;
 112                 *raw = offsettable[i] & 0xff;
 113
 114                 /*
 115                  * Fill in table index.
 116                  */
 117                 raw = offsetbase + offsettable[i] + 2;
 118                 *raw++ = (j & 0xff00) >> 8;
 119                 *raw = j++ & 0xff;
 120         }
 121 }
 122 #endif
 123
 124 isc_result_t
 125 dns_rdataslab_fromrdataset(dns_rdataset_t *rdataset, isc_mem_t *mctx,
 126                            isc_region_t *region, unsigned int reservelen)
 127 {
 128         struct xrdata  *x;
 129         unsigned char  *rawbuf;
 130 #if DNS_RDATASET_FIXED
 131         unsigned char  *offsetbase;
 132 #endif
 133         unsigned int    buflen;
 134         isc_result_t    result;
 135         unsigned int    nitems;
 136         unsigned int    nalloc;
 137         unsigned int    i;
 138 #if DNS_RDATASET_FIXED
 139         unsigned int   *offsettable;
 140 #endif
 141         unsigned int    length;
 142
 143         buflen = reservelen + 2;
 144
 145         nalloc = dns_rdataset_count(rdataset);
 146         nitems = nalloc;
 147         if (nitems == 0)
 148                 return (ISC_R_FAILURE);
 149
 150         if (nalloc > 0xffff)
 151                 return (ISC_R_NOSPACE);
 152
 153         x = isc_mem_get(mctx, nalloc * sizeof(struct xrdata));
 154         if (x == NULL)
 155                 return (ISC_R_NOMEMORY);
 156
 157         /*
 158          * Save all of the rdata members into an array.
 159          */
 160         result = dns_rdataset_first(rdataset);
 161         if (result != ISC_R_SUCCESS)
 162                 goto free_rdatas;
 163         for (i = 0; i < nalloc && result == ISC_R_SUCCESS; i++) {
 164                 INSIST(result == ISC_R_SUCCESS);
 165                 dns_rdata_init(&x[i].rdata);
 166                 dns_rdataset_current(rdataset, &x[i].rdata);
 167 #if DNS_RDATASET_FIXED
 168                 x[i].order = i;
 169 #endif
 170                 result = dns_rdataset_next(rdataset);
 171         }
 172         if (result != ISC_R_NOMORE)
 173                 goto free_rdatas;
 174         if (i != nalloc) {
 175                 /*
 176                  * Somehow we iterated over fewer rdatas than
 177                  * dns_rdataset_count() said there were!
 178                  */
 179                 result = ISC_R_FAILURE;
 180                 goto free_rdatas;
 181         }
 182
 183         /*
 184          * Put into DNSSEC order.
 185          */
 186         qsort(x, nalloc, sizeof(struct xrdata), compare_rdata);
 187
 188         /*
 189          * Remove duplicates and compute the total storage required.
 190          *
 191          * If an rdata is not a duplicate, accumulate the storage size
 192          * required for the rdata.  We do not store the class, type, etc,
 193          * just the rdata, so our overhead is 2 bytes for the number of
 194          * records, and 8 for each rdata, (length(2), offset(4) and order(2))
 195          * and then the rdata itself.
 196          */
 197         for (i = 1; i < nalloc; i++) {
 198                 if (compare_rdata(&x[i-1].rdata, &x[i].rdata) == 0) {
 199                         x[i-1].rdata.data = NULL;
 200                         x[i-1].rdata.length = 0;
 201 #if DNS_RDATASET_FIXED
 202                         /*
 203                          * Preserve the least order so A, B, A -> A, B
 204                          * after duplicate removal.
 205                          */
 206                         if (x[i-1].order < x[i].order)
 207                                 x[i].order = x[i-1].order;
 208 #endif
 209                         nitems--;
 210                 } else {
 211 #if DNS_RDATASET_FIXED
 212                         buflen += (8 + x[i-1].rdata.length);
 213 #else
 214                         buflen += (2 + x[i-1].rdata.length);
 215 #endif
 216                         /*
 217                          * Provide space to store the per RR meta data.
 218                          */
 219                         if (rdataset->type == dns_rdatatype_rrsig)
 220                                 buflen++;
 221                 }
 222         }
 223         /*
 224          * Don't forget the last item!
 225          */
 226 #if DNS_RDATASET_FIXED
 227         buflen += (8 + x[i-1].rdata.length);
 228 #else
 229         buflen += (2 + x[i-1].rdata.length);
 230 #endif
 231         /*
 232          * Provide space to store the per RR meta data.
 233          */
 234         if (rdataset->type == dns_rdatatype_rrsig)
 235                 buflen++;
 236
 237         /*
 238          * Ensure that singleton types are actually singletons.
 239          */
 240         if (nitems > 1 && dns_rdatatype_issingleton(rdataset->type)) {
 241                 /*
 242                  * We have a singleton type, but there's more than one
 243                  * RR in the rdataset.
 244                  */
 245                 result = DNS_R_SINGLETON;
 246                 goto free_rdatas;
 247         }
 248
 249         /*
 250          * Allocate the memory, set up a buffer, start copying in
 251          * data.
 252          */
 253         rawbuf = isc_mem_get(mctx, buflen);
 254         if (rawbuf == NULL) {
 255                 result = ISC_R_NOMEMORY;
 256                 goto free_rdatas;
 257         }
 258
 259 #if DNS_RDATASET_FIXED
 260         /* Allocate temporary offset table. */
 261         offsettable = isc_mem_get(mctx, nalloc * sizeof(unsigned int));
 262         if (offsettable == NULL) {
 263                 isc_mem_put(mctx, rawbuf, buflen);
 264                 result = ISC_R_NOMEMORY;
 265                 goto free_rdatas;
 266         }
 267         memset(offsettable, 0, nalloc * sizeof(unsigned int));
 268 #endif
 269
 270         region->base = rawbuf;
 271         region->length = buflen;
 272
 273         rawbuf += reservelen;
 274 #if DNS_RDATASET_FIXED
 275         offsetbase = rawbuf;
 276 #endif
 277
 278         *rawbuf++ = (nitems & 0xff00) >> 8;
 279         *rawbuf++ = (nitems & 0x00ff);
 280
 281 #if DNS_RDATASET_FIXED
 282         /* Skip load order table.  Filled in later. */
 283         rawbuf += nitems * 4;
 284 #endif
 285
 286         for (i = 0; i < nalloc; i++) {
 287                 if (x[i].rdata.data == NULL)
 288                         continue;
 289 #if DNS_RDATASET_FIXED
 290                 offsettable[x[i].order] = rawbuf - offsetbase;
 291 #endif
 292                 length = x[i].rdata.length;
 293                 if (rdataset->type == dns_rdatatype_rrsig)
 294                         length++;
 295                 *rawbuf++ = (length & 0xff00) >> 8;
 296                 *rawbuf++ = (length & 0x00ff);
 297 #if DNS_RDATASET_FIXED
 298                 rawbuf += 2;    /* filled in later */
 299 #endif
 300                 /*
 301                  * Store the per RR meta data.
 302                  */
 303                 if (rdataset->type == dns_rdatatype_rrsig) {
 304                         *rawbuf++ |= (x[i].rdata.flags & DNS_RDATA_OFFLINE) ?
 305                                             DNS_RDATASLAB_OFFLINE : 0;
 306                 }
 307                 memcpy(rawbuf, x[i].rdata.data, x[i].rdata.length);
 308                 rawbuf += x[i].rdata.length;
 309         }
 310
 311 #if DNS_RDATASET_FIXED
 312         fillin_offsets(offsetbase, offsettable, nalloc);
 313         isc_mem_put(mctx, offsettable, nalloc * sizeof(unsigned int));
 314 #endif
 315
 316         result = ISC_R_SUCCESS;
 317
 318  free_rdatas:
 319         isc_mem_put(mctx, x, nalloc * sizeof(struct xrdata));
 320         return (result);
 321 }
 322
 323 static void
 324 rdataset_disassociate(dns_rdataset_t *rdataset) {
 325         UNUSED(rdataset);
 326 }
 327
 328 static isc_result_t
 329 rdataset_first(dns_rdataset_t *rdataset) {
 330         unsigned char *raw = rdataset->private3;
 331         unsigned int count;
 332
 333         count = raw[0] * 256 + raw[1];
 334         if (count == 0) {
 335                 rdataset->private5 = NULL;
 336                 return (ISC_R_NOMORE);
 337         }
 338 #if DNS_RDATASET_FIXED
 339         raw += 2 + (4 * count);
 340 #else
 341         raw += 2;
 342 #endif
 343         /*
 344          * The privateuint4 field is the number of rdata beyond the cursor
 345          * position, so we decrement the total count by one before storing
 346          * it.
 347          */
 348         count--;
 349         rdataset->privateuint4 = count;
 350         rdataset->private5 = raw;
 351
 352         return (ISC_R_SUCCESS);
 353 }
 354
 355 static isc_result_t
 356 rdataset_next(dns_rdataset_t *rdataset) {
 357         unsigned int count;
 358         unsigned int length;
 359         unsigned char *raw;
 360
 361         count = rdataset->privateuint4;
 362         if (count == 0)
 363                 return (ISC_R_NOMORE);
 364         count--;
 365         rdataset->privateuint4 = count;
 366         raw = rdataset->private5;
 367         length = raw[0] * 256 + raw[1];
 368 #if DNS_RDATASET_FIXED
 369         raw += length + 4;
 370 #else
 371         raw += length + 2;
 372 #endif
 373         rdataset->private5 = raw;
 374
 375         return (ISC_R_SUCCESS);
 376 }
 377
 378 static void
 379 rdataset_current(dns_rdataset_t *rdataset, dns_rdata_t *rdata) {
 380         unsigned char *raw = rdataset->private5;
 381         isc_region_t r;
 382         unsigned int length;
 383         unsigned int flags = 0;
 384
 385         REQUIRE(raw != NULL);
 386
 387         length = raw[0] * 256 + raw[1];
 388 #if DNS_RDATASET_FIXED
 389         raw += 4;
 390 #else
 391         raw += 2;
 392 #endif
 393         if (rdataset->type == dns_rdatatype_rrsig) {
 394                 if (*raw & DNS_RDATASLAB_OFFLINE)
 395                         flags |= DNS_RDATA_OFFLINE;
 396                 length--;
 397                 raw++;
 398         }
 399         r.length = length;
 400         r.base = raw;
 401         dns_rdata_fromregion(rdata, rdataset->rdclass, rdataset->type, &r);
 402         rdata->flags |= flags;
 403 }
 404
 405 static void
 406 rdataset_clone(dns_rdataset_t *source, dns_rdataset_t *target) {
 407         *target = *source;
 408
 409         /*
 410          * Reset iterator state.
 411          */
 412         target->privateuint4 = 0;
 413         target->private5 = NULL;
 414 }
 415
 416 static unsigned int
 417 rdataset_count(dns_rdataset_t *rdataset) {
 418         unsigned char *raw = rdataset->private3;
 419         unsigned int count;
 420
 421         count = raw[0] * 256 + raw[1];
 422
 423         return (count);
 424 }
 425
 426 static dns_rdatasetmethods_t rdataset_methods = {
 427         rdataset_disassociate,
 428         rdataset_first,
 429         rdataset_next,
 430         rdataset_current,
 431         rdataset_clone,
 432         rdataset_count,
 433         NULL,
 434         NULL,
 435         NULL,
 436         NULL,
 437         NULL,
 438         NULL,
 439         NULL
 440 };
 441
 442 void
 443 dns_rdataslab_tordataset(unsigned char *slab, unsigned int reservelen,
 444                          dns_rdataclass_t rdclass, dns_rdatatype_t rdtype,
 445                          dns_rdatatype_t covers, dns_ttl_t ttl,
 446                          dns_rdataset_t *rdataset)
 447 {
 448         REQUIRE(slab != NULL);
 449         REQUIRE(!dns_rdataset_isassociated(rdataset));
 450
 451         rdataset->methods = &rdataset_methods;
 452         rdataset->rdclass = rdclass;
 453         rdataset->type = rdtype;
 454         rdataset->covers = covers;
 455         rdataset->ttl = ttl;
 456         rdataset->trust = 0;
 457         rdataset->private1 = NULL;
 458         rdataset->private2 = NULL;
 459         rdataset->private3 = slab + reservelen;
 460
 461         /*
 462          * Reset iterator state.
 463          */
 464         rdataset->privateuint4 = 0;
 465         rdataset->private5 = NULL;
 466 }
 467
 468 unsigned int
 469 dns_rdataslab_size(unsigned char *slab, unsigned int reservelen) {
 470         unsigned int count, length;
 471         unsigned char *current;
 472
 473         REQUIRE(slab != NULL);
 474
 475         current = slab + reservelen;
 476         count = *current++ * 256;
 477         count += *current++;
 478 #if DNS_RDATASET_FIXED
 479         current += (4 * count);
 480 #endif
 481         while (count > 0) {
 482                 count--;
 483                 length = *current++ * 256;
 484                 length += *current++;
 485 #if DNS_RDATASET_FIXED
 486                 current += length + 2;
 487 #else
 488                 current += length;
 489 #endif
 490         }
 491
 492         return ((unsigned int)(current - slab));
 493 }
 494
 495 /*
 496  * Make the dns_rdata_t 'rdata' refer to the slab item
 497  * beginning at '*current', which is part of a slab of type
 498  * 'type' and class 'rdclass', and advance '*current' to
 499  * point to the next item in the slab.
 500  */
 501 static inline void
 502 rdata_from_slab(unsigned char **current,
 503               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 504               dns_rdata_t *rdata)
 505 {
 506         unsigned char *tcurrent = *current;
 507         isc_region_t region;
 508         unsigned int length;
 509         isc_boolean_t offline = ISC_FALSE;
 510
 511         length = *tcurrent++ * 256;
 512         length += *tcurrent++;
 513
 514         if (type == dns_rdatatype_rrsig) {
 515                 if ((*tcurrent & DNS_RDATASLAB_OFFLINE) != 0)
 516                         offline = ISC_TRUE;
 517                 length--;
 518                 tcurrent++;
 519         }
 520         region.length = length;
 521 #if DNS_RDATASET_FIXED
 522         tcurrent += 2;
 523 #endif
 524         region.base = tcurrent;
 525         tcurrent += region.length;
 526         dns_rdata_fromregion(rdata, rdclass, type, &region);
 527         if (offline)
 528                 rdata->flags |= DNS_RDATA_OFFLINE;
 529         *current = tcurrent;
 530 }
 531
 532 /*
 533  * Return true iff 'slab' (slab data of type 'type' and class 'rdclass')
 534  * contains an rdata identical to 'rdata'.  This does case insensitive
 535  * comparisons per DNSSEC.
 536  */
 537 static inline isc_boolean_t
 538 rdata_in_slab(unsigned char *slab, unsigned int reservelen,
 539               dns_rdataclass_t rdclass, dns_rdatatype_t type,
 540               dns_rdata_t *rdata)
 541 {
 542         unsigned int count, i;
 543         unsigned char *current;
 544         dns_rdata_t trdata = DNS_RDATA_INIT;
 545         int n;
 546
 547         current = slab + reservelen;
 548         count = *current++ * 256;
 549         count += *current++;
 550
 551 #if DNS_RDATASET_FIXED
 552         current += (4 * count);
 553 #endif
 554
 555         for (i = 0; i < count; i++) {
 556                 rdata_from_slab(&current, rdclass, type, &trdata);
 557
 558                 n = dns_rdata_compare(&trdata, rdata);
 559                 if (n == 0)
 560                         return (ISC_TRUE);
 561                 if (n > 0)      /* In DNSSEC order. */
 562                         break;
 563                 dns_rdata_reset(&trdata);
 564         }
 565         return (ISC_FALSE);
 566 }
 567
 568 isc_result_t
 569 dns_rdataslab_merge(unsigned char *oslab, unsigned char *nslab,
 570                     unsigned int reservelen, isc_mem_t *mctx,
 571                     dns_rdataclass_t rdclass, dns_rdatatype_t type,
 572                     unsigned int flags, unsigned char **tslabp)
 573 {
 574         unsigned char *ocurrent, *ostart, *ncurrent, *tstart, *tcurrent, *data;
 575         unsigned int ocount, ncount, count, olength, tlength, tcount, length;
 576         dns_rdata_t ordata = DNS_RDATA_INIT;
 577         dns_rdata_t nrdata = DNS_RDATA_INIT;
 578         isc_boolean_t added_something = ISC_FALSE;
 579         unsigned int oadded = 0;
 580         unsigned int nadded = 0;
 581         unsigned int nncount = 0;
 582 #if DNS_RDATASET_FIXED
 583         unsigned int oncount;
 584         unsigned int norder = 0;
 585         unsigned int oorder = 0;
 586         unsigned char *offsetbase;
 587         unsigned int *offsettable;
 588 #endif
 589
 590         /*
 591          * XXX  Need parameter to allow "delete rdatasets in nslab" merge,
 592          * or perhaps another merge routine for this purpose.
 593          */
 594
 595         REQUIRE(tslabp != NULL && *tslabp == NULL);
 596         REQUIRE(oslab != NULL && nslab != NULL);
 597
 598         ocurrent = oslab + reservelen;
 599         ocount = *ocurrent++ * 256;
 600         ocount += *ocurrent++;
 601 #if DNS_RDATASET_FIXED
 602         ocurrent += (4 * ocount);
 603 #endif
 604         ostart = ocurrent;
 605         ncurrent = nslab + reservelen;
 606         ncount = *ncurrent++ * 256;
 607         ncount += *ncurrent++;
 608 #if DNS_RDATASET_FIXED
 609         ncurrent += (4 * ncount);
 610 #endif
 611         INSIST(ocount > 0 && ncount > 0);
 612
 613 #if DNS_RDATASET_FIXED
 614         oncount = ncount;
 615 #endif
 616
 617         /*
 618          * Yes, this is inefficient!
 619          */
 620
 621         /*
 622          * Figure out the length of the old slab's data.
 623          */
 624         olength = 0;
 625         for (count = 0; count < ocount; count++) {
 626                 length = *ocurrent++ * 256;
 627                 length += *ocurrent++;
 628 #if DNS_RDATASET_FIXED
 629                 olength += length + 8;
 630                 ocurrent += length + 2;
 631 #else
 632                 olength += length + 2;
 633                 ocurrent += length;
 634 #endif
 635         }
 636
 637         /*
 638          * Start figuring out the target length and count.
 639          */
 640         tlength = reservelen + 2 + olength;
 641         tcount = ocount;
 642
 643         /*
 644          * Add in the length of rdata in the new slab that aren't in
 645          * the old slab.
 646          */
 647         do {
 648                 dns_rdata_init(&nrdata);
 649                 rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 650                 if (!rdata_in_slab(oslab, reservelen, rdclass, type, &nrdata))
 651                 {
 652                         /*
 653                          * This rdata isn't in the old slab.
 654                          */
 655 #if DNS_RDATASET_FIXED
 656                         tlength += nrdata.length + 8;
 657 #else
 658                         tlength += nrdata.length + 2;
 659 #endif
 660                         if (type == dns_rdatatype_rrsig)
 661                                 tlength++;
 662                         tcount++;
 663                         nncount++;
 664                         added_something = ISC_TRUE;
 665                 }
 666                 ncount--;
 667         } while (ncount > 0);
 668         ncount = nncount;
 669
 670         if (((flags & DNS_RDATASLAB_EXACT) != 0) &&
 671             (tcount != ncount + ocount))
 672                 return (DNS_R_NOTEXACT);
 673
 674         if (!added_something && (flags & DNS_RDATASLAB_FORCE) == 0)
 675                 return (DNS_R_UNCHANGED);
 676
 677         /*
 678          * Ensure that singleton types are actually singletons.
 679          */
 680         if (tcount > 1 && dns_rdatatype_issingleton(type)) {
 681                 /*
 682                  * We have a singleton type, but there's more than one
 683                  * RR in the rdataset.
 684                  */
 685                 return (DNS_R_SINGLETON);
 686         }
 687
 688         if (tcount > 0xffff)
 689                 return (ISC_R_NOSPACE);
 690
 691         /*
 692          * Copy the reserved area from the new slab.
 693          */
 694         tstart = isc_mem_get(mctx, tlength);
 695         if (tstart == NULL)
 696                 return (ISC_R_NOMEMORY);
 697         memcpy(tstart, nslab, reservelen);
 698         tcurrent = tstart + reservelen;
 699 #if DNS_RDATASET_FIXED
 700         offsetbase = tcurrent;
 701 #endif
 702
 703         /*
 704          * Write the new count.
 705          */
 706         *tcurrent++ = (tcount & 0xff00) >> 8;
 707         *tcurrent++ = (tcount & 0x00ff);
 708
 709 #if DNS_RDATASET_FIXED
 710         /*
 711          * Skip offset table.
 712          */
 713         tcurrent += (tcount * 4);
 714
 715         offsettable = isc_mem_get(mctx,
 716                                   (ocount + oncount) * sizeof(unsigned int));
 717         if (offsettable == NULL) {
 718                 isc_mem_put(mctx, tstart, tlength);
 719                 return (ISC_R_NOMEMORY);
 720         }
 721         memset(offsettable, 0, (ocount + oncount) * sizeof(unsigned int));
 722 #endif
 723
 724         /*
 725          * Merge the two slabs.
 726          */
 727         ocurrent = ostart;
 728         INSIST(ocount != 0);
 729 #if DNS_RDATASET_FIXED
 730         oorder = ocurrent[2] * 256 + ocurrent[3];
 731         INSIST(oorder < ocount);
 732 #endif
 733         rdata_from_slab(&ocurrent, rdclass, type, &ordata);
 734
 735         ncurrent = nslab + reservelen + 2;
 736 #if DNS_RDATASET_FIXED
 737         ncurrent += (4 * oncount);
 738 #endif
 739
 740         if (ncount > 0) {
 741                 do {
 742                         dns_rdata_reset(&nrdata);
 743 #if DNS_RDATASET_FIXED
 744                         norder = ncurrent[2] * 256 + ncurrent[3];
 745
 746                         INSIST(norder < oncount);
 747 #endif
 748                         rdata_from_slab(&ncurrent, rdclass, type, &nrdata);
 749                 } while (rdata_in_slab(oslab, reservelen, rdclass,
 750                                        type, &nrdata));
 751         }
 752
 753         while (oadded < ocount || nadded < ncount) {
 754                 isc_boolean_t fromold;
 755                 if (oadded == ocount)
 756                         fromold = ISC_FALSE;
 757                 else if (nadded == ncount)
 758                         fromold = ISC_TRUE;
 759                 else
 760                         fromold = ISC_TF(compare_rdata(&ordata, &nrdata) < 0);
 761                 if (fromold) {
 762 #if DNS_RDATASET_FIXED
 763                         offsettable[oorder] = tcurrent - offsetbase;
 764 #endif
 765                         length = ordata.length;
 766                         data = ordata.data;
 767                         if (type == dns_rdatatype_rrsig) {
 768                                 length++;
 769                                 data--;
 770                         }
 771                         *tcurrent++ = (length & 0xff00) >> 8;
 772                         *tcurrent++ = (length & 0x00ff);
 773 #if DNS_RDATASET_FIXED
 774                         tcurrent += 2;  /* fill in later */
 775 #endif
 776                         memcpy(tcurrent, data, length);
 777                         tcurrent += length;
 778                         oadded++;
 779                         if (oadded < ocount) {
 780                                 dns_rdata_reset(&ordata);
 781 #if DNS_RDATASET_FIXED
 782                                 oorder = ocurrent[2] * 256 + ocurrent[3];
 783                                 INSIST(oorder < ocount);
 784 #endif
 785                                 rdata_from_slab(&ocurrent, rdclass, type,
 786                                                 &ordata);
 787                         }
 788                 } else {
 789 #if DNS_RDATASET_FIXED
 790                         offsettable[ocount + norder] = tcurrent - offsetbase;
 791 #endif
 792                         length = nrdata.length;
 793                         data = nrdata.data;
 794                         if (type == dns_rdatatype_rrsig) {
 795                                 length++;
 796                                 data--;
 797                         }
 798                         *tcurrent++ = (length & 0xff00) >> 8;
 799                         *tcurrent++ = (length & 0x00ff);
 800 #if DNS_RDATASET_FIXED
 801                         tcurrent += 2;  /* fill in later */
 802 #endif
 803                         memcpy(tcurrent, data, length);
 804                         tcurrent += length;
 805                         nadded++;
 806                         if (nadded < ncount) {
 807                                 do {
 808                                         dns_rdata_reset(&nrdata);
 809 #if DNS_RDATASET_FIXED
 810                                         norder = ncurrent[2] * 256 + ncurrent[3];
 811                                         INSIST(norder < oncount);
 812 #endif
 813                                         rdata_from_slab(&ncurrent, rdclass,
 814                                                         type, &nrdata);
 815                                 } while (rdata_in_slab(oslab, reservelen,
 816                                                        rdclass, type,
 817                                                        &nrdata));
 818                         }
 819                 }
 820         }
 821
 822 #if DNS_RDATASET_FIXED
 823         fillin_offsets(offsetbase, offsettable, ocount + oncount);
 824
 825         isc_mem_put(mctx, offsettable,
 826                     (ocount + oncount) * sizeof(unsigned int));
 827 #endif
 828
 829         INSIST(tcurrent == tstart + tlength);
 830
 831         *tslabp = tstart;
 832
 833         return (ISC_R_SUCCESS);
 834 }
 835
 836 isc_result_t
 837 dns_rdataslab_subtract(unsigned char *mslab, unsigned char *sslab,
 838                        unsigned int reservelen, isc_mem_t *mctx,
 839                        dns_rdataclass_t rdclass, dns_rdatatype_t type,
 840                        unsigned int flags, unsigned char **tslabp)
 841 {
 842         unsigned char *mcurrent, *sstart, *scurrent, *tstart, *tcurrent;
 843         unsigned int mcount, scount, rcount ,count, tlength, tcount, i;
 844         dns_rdata_t srdata = DNS_RDATA_INIT;
 845         dns_rdata_t mrdata = DNS_RDATA_INIT;
 846 #if DNS_RDATASET_FIXED
 847         unsigned char *offsetbase;
 848         unsigned int *offsettable;
 849         unsigned int order;
 850 #endif
 851
 852         REQUIRE(tslabp != NULL && *tslabp == NULL);
 853         REQUIRE(mslab != NULL && sslab != NULL);
 854
 855         mcurrent = mslab + reservelen;
 856         mcount = *mcurrent++ * 256;
 857         mcount += *mcurrent++;
 858         scurrent = sslab + reservelen;
 859         scount = *scurrent++ * 256;
 860         scount += *scurrent++;
 861         INSIST(mcount > 0 && scount > 0);
 862
 863         /*
 864          * Yes, this is inefficient!
 865          */
 866
 867         /*
 868          * Start figuring out the target length and count.
 869          */
 870         tlength = reservelen + 2;
 871         tcount = 0;
 872         rcount = 0;
 873
 874 #if DNS_RDATASET_FIXED
 875         mcurrent += 4 * mcount;
 876         scurrent += 4 * scount;
 877 #endif
 878         sstart = scurrent;
 879
 880         /*
 881          * Add in the length of rdata in the mslab that aren't in
 882          * the sslab.
 883          */
 884         for (i = 0; i < mcount; i++) {
 885                 unsigned char *mrdatabegin = mcurrent;
 886                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 887                 scurrent = sstart;
 888                 for (count = 0; count < scount; count++) {
 889                         dns_rdata_reset(&srdata);
 890                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 891                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 892                                 break;
 893                 }
 894                 if (count == scount) {
 895                         /*
 896                          * This rdata isn't in the sslab, and thus isn't
 897                          * being subtracted.
 898                          */
 899                         tlength += mcurrent - mrdatabegin;
 900                         tcount++;
 901                 } else
 902                         rcount++;
 903                 dns_rdata_reset(&mrdata);
 904         }
 905
 906 #if DNS_RDATASET_FIXED
 907         tlength += (4 * tcount);
 908 #endif
 909
 910         /*
 911          * Check that all the records originally existed.  The numeric
 912          * check only works as rdataslabs do not contain duplicates.
 913          */
 914         if (((flags & DNS_RDATASLAB_EXACT) != 0) && (rcount != scount))
 915                 return (DNS_R_NOTEXACT);
 916
 917         /*
 918          * Don't continue if the new rdataslab would be empty.
 919          */
 920         if (tcount == 0)
 921                 return (DNS_R_NXRRSET);
 922
 923         /*
 924          * If nothing is going to change, we can stop.
 925          */
 926         if (rcount == 0)
 927                 return (DNS_R_UNCHANGED);
 928
 929         /*
 930          * Copy the reserved area from the mslab.
 931          */
 932         tstart = isc_mem_get(mctx, tlength);
 933         if (tstart == NULL)
 934                 return (ISC_R_NOMEMORY);
 935         memcpy(tstart, mslab, reservelen);
 936         tcurrent = tstart + reservelen;
 937 #if DNS_RDATASET_FIXED
 938         offsetbase = tcurrent;
 939
 940         offsettable = isc_mem_get(mctx, mcount * sizeof(unsigned int));
 941         if (offsettable == NULL) {
 942                 isc_mem_put(mctx, tstart, tlength);
 943                 return (ISC_R_NOMEMORY);
 944         }
 945         memset(offsettable, 0, mcount * sizeof(unsigned int));
 946 #endif
 947
 948         /*
 949          * Write the new count.
 950          */
 951         *tcurrent++ = (tcount & 0xff00) >> 8;
 952         *tcurrent++ = (tcount & 0x00ff);
 953
 954 #if DNS_RDATASET_FIXED
 955         tcurrent += (4 * tcount);
 956 #endif
 957
 958         /*
 959          * Copy the parts of mslab not in sslab.
 960          */
 961         mcurrent = mslab + reservelen;
 962         mcount = *mcurrent++ * 256;
 963         mcount += *mcurrent++;
 964 #if DNS_RDATASET_FIXED
 965         mcurrent += (4 * mcount);
 966 #endif
 967         for (i = 0; i < mcount; i++) {
 968                 unsigned char *mrdatabegin = mcurrent;
 969 #if DNS_RDATASET_FIXED
 970                 order = mcurrent[2] * 256 + mcurrent[3];
 971                 INSIST(order < mcount);
 972 #endif
 973                 rdata_from_slab(&mcurrent, rdclass, type, &mrdata);
 974                 scurrent = sstart;
 975                 for (count = 0; count < scount; count++) {
 976                         dns_rdata_reset(&srdata);
 977                         rdata_from_slab(&scurrent, rdclass, type, &srdata);
 978                         if (dns_rdata_compare(&mrdata, &srdata) == 0)
 979                                 break;
 980                 }
 981                 if (count == scount) {
 982                         /*
 983                          * This rdata isn't in the sslab, and thus should be
 984                          * copied to the tslab.
 985                          */
 986                         unsigned int length = mcurrent - mrdatabegin;
 987 #if DNS_RDATASET_FIXED
 988                         offsettable[order] = tcurrent - offsetbase;
 989 #endif
 990                         memcpy(tcurrent, mrdatabegin, length);
 991                         tcurrent += length;
 992                 }
 993                 dns_rdata_reset(&mrdata);
 994         }
 995
 996 #if DNS_RDATASET_FIXED
 997         fillin_offsets(offsetbase, offsettable, mcount);
 998
 999         isc_mem_put(mctx, offsettable, mcount * sizeof(unsigned int));
1000 #endif
1001
1002         INSIST(tcurrent == tstart + tlength);
1003
1004         *tslabp = tstart;
1005
1006         return (ISC_R_SUCCESS);
1007 }
1008
1009 isc_boolean_t
1010 dns_rdataslab_equal(unsigned char *slab1, unsigned char *slab2,
1011                     unsigned int reservelen)
1012 {
1013         unsigned char *current1, *current2;
1014         unsigned int count1, count2;
1015         unsigned int length1, length2;
1016
1017         current1 = slab1 + reservelen;
1018         count1 = *current1++ * 256;
1019         count1 += *current1++;
1020
1021         current2 = slab2 + reservelen;
1022         count2 = *current2++ * 256;
1023         count2 += *current2++;
1024
1025         if (count1 != count2)
1026                 return (ISC_FALSE);
1027
1028 #if DNS_RDATASET_FIXED
1029         current1 += (4 * count1);
1030         current2 += (4 * count2);
1031 #endif
1032
1033         while (count1 > 0) {
1034                 length1 = *current1++ * 256;
1035                 length1 += *current1++;
1036
1037                 length2 = *current2++ * 256;
1038                 length2 += *current2++;
1039
1040 #if DNS_RDATASET_FIXED
1041                 current1 += 2;
1042                 current2 += 2;
1043 #endif
1044
1045                 if (length1 != length2 ||
1046                     memcmp(current1, current2, length1) != 0)
1047                         return (ISC_FALSE);
1048
1049                 current1 += length1;
1050                 current2 += length1;
1051
1052                 count1--;
1053         }
1054         return (ISC_TRUE);
1055 }
1056
1057 isc_boolean_t
1058 dns_rdataslab_equalx(unsigned char *slab1, unsigned char *slab2,
1059                      unsigned int reservelen, dns_rdataclass_t rdclass,
1060                      dns_rdatatype_t type)
1061 {
1062         unsigned char *current1, *current2;
1063         unsigned int count1, count2;
1064         dns_rdata_t rdata1 = DNS_RDATA_INIT;
1065         dns_rdata_t rdata2 = DNS_RDATA_INIT;
1066
1067         current1 = slab1 + reservelen;
1068         count1 = *current1++ * 256;
1069         count1 += *current1++;
1070
1071         current2 = slab2 + reservelen;
1072         count2 = *current2++ * 256;
1073         count2 += *current2++;
1074
1075         if (count1 != count2)
1076                 return (ISC_FALSE);
1077
1078 #if DNS_RDATASET_FIXED
1079         current1 += (4 * count1);
1080         current2 += (4 * count2);
1081 #endif
1082
1083         while (count1-- > 0) {
1084                 rdata_from_slab(&current1, rdclass, type, &rdata1);
1085                 rdata_from_slab(&current2, rdclass, type, &rdata2);
1086                 if (dns_rdata_compare(&rdata1, &rdata2) != 0)
1087                         return (ISC_FALSE);
1088                 dns_rdata_reset(&rdata1);
1089                 dns_rdata_reset(&rdata2);
1090         }
1091         return (ISC_TRUE);
1092 }